Tag: diffusion

Questions Related to diffusion

Diffusion is more rapid in liquid than in gases.

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Diffusion is more rapid in gas as compared to liquid, this is because gases have more kinetic energy and gas molecules are smaller compared to liquid molecules. When the temperature is raised, this results in the increase of kinetic energy of the molecules and rate of diffusion is also increased.

So, the correct answer is option B.

Plasma membrane does not have carrier molecules for

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. Active transport

  2. Simple diffusion

  3. Faciliated diffusion

  4. $Na^+-K^+$ pump

Show answer
Correct Option: B
Explanation:

In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers.
For active transport, as the movement is against the concentration gradient, carriers or pumps are required. Similarly with Na-K pump.
Simple diffusion is just the movement of molecules from a place of higher concentration to lower concentration without any carrier molecules.
Thus, the correct answer is option (B). 

Cell wall shows

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. Semi permeability

  2. Selective permeability

  3. Complete permeability

  4. Impermeability

Show answer
Correct Option: B
Explanation:

Cell wall is the outer protective layer of a cell. Cellulose is an important constituent of the cell wall. It is made up of carbon, hydrogen and oxygen. It is is selectively permeable, as it allows molecules upto 30-60kD to pass easily without the expenditure of energy and fully permeable to water and proteins molecules.

Differential permeability is a semipermeable membrane which is almost completely impermeable to solute molecules, but is permeable to the solvent.
Complete permeability is a membrane which is almost completely permeable to all the solute and solvent molecules.
Semipermeable membrane allows certain molecules or ions to pass through it by diffusion
So, the correct answer is option ' Selectively permeable'.

The movement of free atoms from higher concentration to lower concentration is called:

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. Osmosis

  2. Diffusion

  3. Endosmosis

  4. Exosmosis

Show answer
Correct Option: B
Explanation:

Osmosis is the movement of solvent through a semi-permeable membrane to a region of higher solute concentration.

Diffusion is a process of movement of ions or molecules from a higher concentration to an area of lower concentration.
Endosmosis is the process of movement of solvent from outside to the inside of the cell.
While, exosmosis is the process of movement of solvent from inside to the outside of the cell.
Thus, the correct answer is option (B). 


State whether the following statements are true or false.
Lipid-soluble molecules are able to diffuse into a cell more rapidly than water-soluble molecules.

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Fat-soluble molecules, such as steroids, alcohols, and some vitamins, can dissolve in the lipid portion of the membrane and diffuse in and out the cell. Water soluble molecules can't pass through the hydrophobic portion of the phospholipid layer.

So, the correct option is 'True'.

Which one of the following process of transporting substances across a membrane does not involve a change in the shape of the transport protein?

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. Active transport

  2. $Na^+ - K^+$ pump

  3. Simple diffusion

  4. Facilitated diffusion

Show answer
Correct Option: C
Explanation:

Both active transport and facilitated diffusion are mediated through membrane proteins, here channel proteins allow diffusion of solutes of appropriate size only, so in this size and shape of transport protein changes while simple diffusion does not require proteins for transportation.

 So, the correct option is 'Simple diffusion'.

The given table shows properties of four cells systems A, B, C and D. The maximum rate of inward diffusion of water will be observed in which of these systems?

System Intracellular concentration of water Extracellular concentration of water
A $0.09$M $0.11$M
B $0.2$M $0.5$M
C $0.05$M $0.7$M
D $0.03$M $0.6$M
bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. System A

  2. System B

  3. System C

  4. System D

Show answer
Correct Option: C
Explanation:
Diffusion of water will occur from higher concentration to lower concentration. Maximum rate of inward diffusion of water will occur where concentration difference is maximum. System C has maximum concentration difference of 0.65M. Hence, maximum diffusion will occur in system C.

So, the correct answer is 'System C'.

Movement of the molecules of solids, gases or liquids from the region of their higher concentration to the region of their lower concentration is known as ___________.

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. Diffusion

  2. Osmosis

  3. Imbibition

  4. Active transport

Show answer
Correct Option: A
Explanation:

Diffusion is the movement of the particles of different substances from the region of their higher concentration, free energy or diffusion pressure to the region of their lower concentration, free energy or diffusion pressure.

Water in adjacent xylem moves into the phloem by process of :

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. Simple diffusion

  2. Active transport

  3. Osmosis

  4. Facilitated diffusion

Show answer
Correct Option: C
Explanation:

Water is passively transported into the roots and then into the xylem. The forces of cohesion and adhesion cause the water molecules to form a column in the xylem. Water moves from the xylem into the mesophyll cells, evaporates from their surfaces and leaves by diffusion through the stomata. The increased solute concentration causes water to move by osmosis from the xylem into the phloem. The positive pressure that is produced pushes water and solutes down the pressure gradient. So, the correct answer is "Osmosis".

In photosynthesis, oxygen is given out by the process of

bio-chemistry absorption by roots - the processes involved diffusion transport across membrane means of transport

  1. Diffusion 

  2. Osmosis

  3. Transpiration

  4. None of the above

Show answer
Correct Option: A
Explanation:

Diffusion is a process in which the molecules intermingle due to their kinetic energy and movement of molecules is from higher concentration to lower concentration. During photosynthesis, the plant produces oxygen as a byproduct and hence the concentration of oxygen inside the cell is higher than the outer environment. Plant releases oxygen in external environment through diffusion process.